Skip to main content
Porffor implements the full String API for string manipulation and processing.

​
String Methods

​
charAt

Returns the character at the specified index. 
string.charAt(index: number): string

const str = 'Hello';
console.log(str.charAt(0));  // 'H'
console.log(str.charAt(4));  // 'o'
console.log(str.charAt(10)); // '' (empty string)

​
charCodeAt

Returns the Unicode value of the character at the specified index. 
string.charCodeAt(index: number): number

const str = 'ABC';
console.log(str.charCodeAt(0)); // 65 (A)
console.log(str.charCodeAt(1)); // 66 (B)
console.log(str.charCodeAt(2)); // 67 (C)

​
concat

Concatenates strings. 
string.concat(...strings: string[]): string

const str1 = 'Hello';
const str2 = str1.concat(' ', 'World', '!');
console.log(str2); // 'Hello World!'

​
indexOf

Returns the first index of a substring, or -1 if not found. 
string.indexOf(searchString: string, position?: number): number

const str = 'Hello World';
console.log(str.indexOf('o'));      // 4
console.log(str.indexOf('o', 5));   // 7
console.log(str.indexOf('xyz'));    // -1

​
lastIndexOf

Returns the last index of a substring. 
string.lastIndexOf(searchString: string, position?: number): number

const str = 'Hello World';
console.log(str.lastIndexOf('o'));  // 7
console.log(str.lastIndexOf('l'));  // 9

​
slice

Extracts a section of a string. 
string.slice(start: number, end?: number): string

const str = 'Hello World';
console.log(str.slice(0, 5));   // 'Hello'
console.log(str.slice(6));      // 'World'
console.log(str.slice(-5));     // 'World'
console.log(str.slice(0, -6));  // 'Hello'

​
substring

Returns a substring between two indices. 
string.substring(start: number, end?: number): string

const str = 'Hello World';
console.log(str.substring(0, 5));  // 'Hello'
console.log(str.substring(6));     // 'World'
console.log(str.substring(6, 11)); // 'World'

​
substr

Returns a substring starting at a position with specified length. 
string.substr(start: number, length?: number): string

const str = 'Hello World';
console.log(str.substr(0, 5));  // 'Hello'
console.log(str.substr(6, 5));  // 'World'
console.log(str.substr(-5, 5)); // 'World'

​
toLowerCase

Converts string to lowercase. 
string.toLowerCase(): string

const str = 'Hello World';
console.log(str.toLowerCase()); // 'hello world'

​
toUpperCase

Converts string to uppercase. 
string.toUpperCase(): string

const str = 'Hello World';
console.log(str.toUpperCase()); // 'HELLO WORLD'

​
trim

Removes whitespace from both ends. 
string.trim(): string

const str = '  Hello World  ';
console.log(str.trim()); // 'Hello World'

​
trimStart / trimLeft

Removes whitespace from the start. 
string.trimStart(): string

const str = '  Hello World  ';
console.log(str.trimStart()); // 'Hello World  '

​
trimEnd / trimRight

Removes whitespace from the end. 
string.trimEnd(): string

const str = '  Hello World  ';
console.log(str.trimEnd()); // '  Hello World'

​
split

Splits string into an array of substrings. 
string.split(separator?: string | RegExp, limit?: number): string[]

const str = 'a,b,c,d';
console.log(str.split(','));      // ['a', 'b', 'c', 'd']
console.log(str.split(',', 2));   // ['a', 'b']
console.log('hello'.split(''));   // ['h', 'e', 'l', 'l', 'o']

​
replace

Replaces occurrences of a substring or pattern. 
string.replace(searchValue: string | RegExp, replaceValue: string): string

const str = 'Hello World';
console.log(str.replace('World', 'Porffor')); // 'Hello Porffor'
console.log(str.replace(/o/g, '0'));          // 'Hell0 W0rld'

​
replaceAll

Replaces all occurrences of a substring. 
string.replaceAll(searchValue: string | RegExp, replaceValue: string): string

const str = 'aabbcc';
console.log(str.replaceAll('b', 'x')); // 'aaxxcc'

​
match

Matches a string against a regular expression. 
string.match(regexp: RegExp): string[] | null

const str = 'The year is 2024';
const matches = str.match(/\d+/);
console.log(matches); // ['2024']

const globalMatches = 'a1 b2 c3'.match(/\d/g);
console.log(globalMatches); // ['1', '2', '3']
Searches for a match and returns the index. 
string.search(regexp: RegExp): number

const str = 'Hello World';
console.log(str.search(/World/));  // 6
console.log(str.search(/xyz/));    // -1

​
startsWith

Checks if string starts with specified substring. 
string.startsWith(searchString: string, position?: number): boolean

const str = 'Hello World';
console.log(str.startsWith('Hello'));     // true
console.log(str.startsWith('World'));     // false
console.log(str.startsWith('World', 6));  // true

​
endsWith

Checks if string ends with specified substring. 
string.endsWith(searchString: string, length?: number): boolean

const str = 'Hello World';
console.log(str.endsWith('World'));    // true
console.log(str.endsWith('Hello'));    // false
console.log(str.endsWith('Hello', 5)); // true

​
includes

Checks if string contains a substring. 
string.includes(searchString: string, position?: number): boolean

const str = 'Hello World';
console.log(str.includes('World'));    // true
console.log(str.includes('xyz'));      // false
console.log(str.includes('World', 7)); // false

​
repeat

Repeats the string a specified number of times. 
string.repeat(count: number): string

console.log('abc'.repeat(3));   // 'abcabcabc'
console.log('*'.repeat(5));     // '*****'

​
padStart

Pads the string from the start. 
string.padStart(targetLength: number, padString?: string): string

const str = '5';
console.log(str.padStart(3, '0'));   // '005'
console.log('abc'.padStart(10, '*')); // '*******abc'

​
padEnd

Pads the string from the end. 
string.padEnd(targetLength: number, padString?: string): string

const str = '5';
console.log(str.padEnd(3, '0'));     // '500'
console.log('abc'.padEnd(10, '*'));  // 'abc*******'

​
at

Returns the character at an index (supports negative indexing). 
string.at(index: number): string | undefined

const str = 'Hello';
console.log(str.at(0));   // 'H'
console.log(str.at(-1));  // 'o'
console.log(str.at(-2));  // 'l'

​
Static Methods

​
String.fromCharCode

Creates a string from character codes. 
String.fromCharCode(...codes: number[]): string

console.log(String.fromCharCode(72, 101, 108, 108, 111)); // 'Hello'
console.log(String.fromCharCode(65, 66, 67));             // 'ABC'

​
Usage Examples

​
Text Processing

function normalizeWhitespace(text) {
  return text.trim().replace(/\s+/g, ' ');
}

console.log(normalizeWhitespace('  hello    world  '));
// 'hello world'

​
String Validation

function isValidEmail(email) {
  return email.includes('@') && 
         email.indexOf('@') > 0 && 
         email.indexOf('@') < email.length - 1;
}

console.log(isValidEmail('user@example.com')); // true
console.log(isValidEmail('invalid'));          // false

​
Case Conversion

function toTitleCase(str) {
  return str.toLowerCase()
    .split(' ')
    .map(word => word.charAt(0).toUpperCase() + word.slice(1))
    .join(' ');
}

console.log(toTitleCase('hello world')); // 'Hello World'

​
See Also

Build docs developers (and LLMs) love

Get started for freeTalk to us